Energy absorption device

Abstract

The invention relates to an energy absorption device for a bumper (4) of a motor vehicle. The energy absorption device has a first deformation element (8) on the front side of the bumper (4). The first deformation element (8) is a foam shaped part which extends over the width of the bumper (4) and has a density of from 20 to 50 g / l. At least one second deformation element (10), with a density which is at least 50 g / l higher than the first deformation element (8), is inserted into the first deformation element (8).

Description

[0001] The invention relates to an energy absorption device for a bumper of a vehicle, in particular a motor vehicle, according to the preamble of claim 1, and to a motor vehicle according to claim 8.

[0002] From DE 10 2015 209 746 A1, an energy absorption device for a motor vehicle bumper is known, which is arranged on the front of a bumper designed as a cross member. The known energy absorption device comprises a first deformation element forming a "base body" (referred to as the "second deformation element" in the terminology of DE 10 2015 209 746 A1) and local second deformation elements (referred to as the "third deformation element" in the terminology of DE 10 2015 209 746 A1). The second deformation elements are preferably arranged in line with the longitudinal members of the motor vehicle.

[0003] From JP S60 143161 A, an energy absorption device for a vehicle bumper is known. This device comprises a first deformation element extending substantially across the entire width of the bumper and at least one second deformation element arranged on the first deformation element, wherein the first and second deformation elements consist of foam materials of different densities. The deformation elements consist of foamed polyethylene and polypropylene, respectively, wherein the foam material of the first deformation element is expanded 30 to 50 times and that of the second deformation element is expanded 10 times. The second deformation element is arranged below or on an underside of the first deformation element.

[0004] From DE 10 2006 041 095 A1, an energy absorption device for a vehicle bumper is known. This energy absorption device has a first deformation element and at least two second deformation elements arranged on the first deformation element. The first and second deformation elements are made of foamed plastic of different densities, with the density of the second deformation elements being lower. The second deformation elements have a smaller extent in the transverse and longitudinal directions of the vehicle and are arranged symmetrically to a longitudinal center plane of the vehicle in the region of the extension of the front longitudinal members of the vehicle.

[0005] US Patent 2013 / 257070 A1 describes an energy absorption device for a vehicle bumper, in which a first deformation element has a central recess in which two second deformation elements are arranged. The first and second deformation elements are made of foamed resin, the first deformation element having a relatively low expansion ratio and the second deformation elements having a relatively high expansion ratio.

[0006] CN105799625A discloses an energy absorption device for a vehicle bumper, comprising a first deformation element extending substantially over the entire width of the bumper and at least two second deformation elements arranged on the first deformation element, wherein the first and second deformation elements consist of foam materials of different densities, wherein the first deformation element has a recess for receiving the second deformation element, and the second deformation element is inserted into the first deformation element and has a smaller extent in the transverse, vertical, and longitudinal directions of the vehicle compared to the first deformation element, and wherein the at least two second deformation elements are arranged in a mirror-symmetrical manner with respect to a longitudinal center plane of the vehicle in the region of the extension of front longitudinal members of the vehicle.

[0007] The object of the invention is to provide an energy absorption device which has improved properties.

[0008] This problem is solved by an energy absorption device with the features of claim 1. Claim 8 relates to a motor vehicle with an energy absorption device according to the invention.

[0009] The core idea of ​​the invention is to provide an energy absorption device made of a composite foam component whose components have significantly different densities and thus significantly different stiffnesses. According to the invention, the foam material of the first deformation element has a density at least 50 g / l lower than that of the second deformation element ("density difference"). In an embodiment of the invention, the foam material of the first deformation element has a density at least 60 g / l lower than that of the second deformation element. In a further embodiment of the invention, the foam material of the first deformation element has a density at least 70 g / l lower than that of the second deformation element.

[0010] Furthermore, according to the invention, the density of the foam material of the first deformation element is 20 to 50 g / l ("density 1"). In an embodiment of the invention, the density of the foam material of the first deformation element is 25 to 40 g / l. In a further embodiment of the invention, the density of the foam material of the first deformation element is 25 to 35 g / l.

[0011] Furthermore, according to the invention, the density of the foam material of the second deformation element is 80 to 250 g / l ("density 2"). In an embodiment of the invention, the density of the foam material of the second deformation element is 90 to 250 g / l. In a further embodiment of the invention, the density of the foam material of the second deformation element is 100 to 250 g / l.

[0012] All density values ​​are subject to a tolerance of + / - 10%.

[0013] The invention includes any combinations of the "density gap" with the "density 1" and the "density 2", i.e. pairings of first and second deformation elements with a defined difference in the density of the foam materials of the two deformation elements.

[0014] Generally, a larger absolute "density difference" is useful when "density 1" has a value at the upper end of the specified range, compared to a value of "density 1" at the lower end of the specified range. This results in a comparable relative "density difference" in both cases.

[0015] The specified value ranges for the densities of the foam materials of the first and second deformation elements were determined by the applicant using new approaches in extensive investigations, in which it was necessary to resolve the partly contradictory requirements between pedestrian protection and "low speed crash".

[0016] The first deformation element is fundamentally designed in its energy absorption behavior to meet the requirements of pedestrian protection.

[0017] Furthermore, to accommodate a higher load input in a so-called "low-speed crash" (collision speed < 20 km / h), the energy absorption device according to the invention provides at least a second deformation element with greater stiffness. Thus, the energy absorption device according to the invention fulfills the requirements of both pedestrian protection and low-speed crash testing.

[0018] A "low-speed crash" refers, for example, to minor parking collisions or rear-end collisions at low speed (or low residual speed after prior braking). Such collisions are generally below the deployment threshold of the airbag system, which protects the vehicle's occupants. The damage to the vehicle in a "low-speed crash" is considered minor, meaning there is no damage to the vehicle's load-bearing structure. Nevertheless, it is crucial for limiting the damage to the vehicle that as much collision energy as possible is absorbed by the airbag system. This reduces repair costs and can lead to a more favorable comprehensive insurance rating.

[0019] The invention is characterized in that the second deformation element forms a local stiffening of the first deformation element. The first deformation element can form a "base body" that incorporates the second deformation element within itself or on itself. The second deformation element is inserted at certain positions of the first deformation element.

[0020] The position and / or size of the second deformation element depends on the vehicle's design, particularly the design of the bumper and / or the first deformation element. The design of the energy absorption device is typically carried out in tests with test specimens (e.g., barriers, pendulums). For example, the position and / or size of the second deformation element are dimensioned to ensure sufficient geometric overlap with commonly used test specimens, while simultaneously maximizing the extent of the first deformation element. This ensures that the overall system meets the requirements of both pedestrian protection and low-speed crash tests.

[0021] The invention thus resolves the conflict of objectives between pedestrian protection and "low speed crash", taking into account the requirements arising from the available installation space in the vehicle and the vehicle proportions specified by the vehicle's package.

[0022] In the "low speed crash", the intrusion of the test specimen is reduced to a minimum by the second deformation element, in order to minimize vehicle damage, while simultaneously fulfilling pedestrian protection requirements through targeted energy dissipation in the first deformation element.

[0023] The second deformation element has no significant influence on pedestrian protection due to its positioning on or within the first deformation element and / or due to its shape and / or size.

[0024] In this embodiment of the invention, the second deformation element is dimensioned such that it does not affect the sensing of a pedestrian's impact, for example by a pressure hose. This sensing serves, for example, to trigger actuators for an active front flap.

[0025] With regard to different vehicle models from a vehicle manufacturer and / or variants of a vehicle model and / or country-specific versions of a vehicle model, the invention makes it possible in a simple manner to achieve individual adaptation through appropriate pairings of first and second deformation elements. The deformation elements of the individual vehicle variants can differ, for example, in their density and / or their geometry (width, height, thickness), as well as with regard to the arrangement of the second deformation element on or within the first deformation element.

[0026] The invention makes it possible to reduce the required installation space in the longitudinal direction of the vehicle, between the bumper cover and the front of the bumper, without compromising pedestrian protection and / or the requirements of the low-speed crash test. This reduces the body overhang in front of the front axle, which has a positive effect on the vehicle's external appearance. As mentioned above, the increased energy absorption of the second deformation element results in less crash-induced intrusion (and thus reduced damage to the vehicle), with advantages regarding the vehicle's insurance classification. Furthermore, less deformation clearance is required behind the bumper, for example, for a radiator located behind the bumper.

[0027] The second deformation element has a smaller extent in the transverse and vertical directions of the vehicle, as well as in the longitudinal direction, compared to the first deformation element. The second deformation element therefore represents a local stiffening within the energy absorption device.

[0028] According to the invention, at least two second deformation elements are provided, which are arranged, for example, in a mirror-symmetrical manner to a longitudinal center plane of the vehicle, on or in the right and left sections of the first deformation element.

[0029] The second set of deformation elements is located in the area where the front longitudinal members of the vehicle extend. These front longitudinal members are also known as engine mounts and support the bumper at their front ends. The front longitudinal members have so-called "defoboxes" in their front section to absorb energy in the event of a crash. The force level at which the second set of deformation elements deforms is, for example, slightly lower than the force level at which the "defoboxes" deform. This design ensures that the second set of deformation elements is compressed, possibly to the point of locking, before the "defobox" is activated.

[0030] Naturally, more than two second deformation elements can be provided. In addition to the paired arrangement of the second deformation elements, a single second deformation element, preferably arranged centrally on or within the first deformation element, can also be provided.

[0031] The first deformation element can extend continuously over at least almost the entire width of the bumper.

[0032] According to the invention, the second deformation element is inserted into the first deformation element.

[0033] For this purpose, recesses are provided in the first deformation element, each of which accommodates the second deformation element. This results in a reduced material thickness of the first deformation element in the area where the second deformation element is inserted.

[0034] According to the invention, the second deformation element is arranged on the front side of the first deformation element, i.e. adjacent to the adjacent bumper trim, or inserted into the rear side of the first deformation element, adjacent to the adjacent bumper.

[0035] The second deformation element can be cuboid-shaped or pyramid-shaped. Alternatively, the second deformation element can be strip-shaped. In both configurations, the second deformation element can be located on the front and / or back of the first deformation element.

[0036] In an advantageous embodiment of the invention, the first deformation element is positioned opposite the second deformation element, so that in the event of a collision, the first deformation element is compressed first. As already explained above, however, the first deformation element can also be arranged "behind" or "inside" the second deformation element.

[0037] However, all the above-mentioned embodiments have in common that, due to the lower density of the first deformation element, the first deformation element is compressed first, before the second deformation element is subsequently compressed.

[0038] All position designations used above refer to the installation position of an energy absorption device according to the invention in a vehicle.

[0039] The energy absorption device according to the invention, which consists of the "base body" of the first deformation element and the second deformation element inserted therein or connected to it, can be manufactured in different ways. On the one hand, it can be a "built energy absorption device" with separately manufactured and subsequently assembled foam components. On the other hand, the energy absorption device can consist of inseparably bonded foam components ("multi-component foam components").

[0040] In a "built-in energy absorption device," the first and second deformation elements are manufactured separately. In this embodiment of the invention, the first deformation element has a recess for receiving the second deformation element. The second deformation element is inserted into the recess of the first deformation element and fixed in place, for example, by a positive-locking connection. This positive-locking connection can be achieved, for example, by inserting the second deformation element (a "rigid foam component") into the first deformation element, such as into an undercut or along inclined surfaces of the first deformation element. Alternatively or additionally, the second deformation element can be bonded to the first deformation element.

[0041] Alternatively or additionally, supplementary elements such as clips may be provided to fix the second deformation element to the first deformation element.

[0042] In the preceding description, the singular form is generally used in connection with the "second deformation element", in the sense that it is "at least a second deformation element".

[0043] The invention further relates to a motor vehicle with an energy absorption device according to the invention.

[0044] Possible embodiments of the invention are shown in the drawing and are explained in more detail below. It shows: Fig. 1 a schematic representation of a bumper arrangement with an energy absorption device according to the prior art (left half of Fig. 1 ) or an energy absorption device according to the invention (right half of Fig. 1 ), Fig. 2 a perspective view of a first deformation element for a bumper, according to the prior art, Fig. 3 one of the Fig. 2 A corresponding representation of a first deformation element according to the invention with inserted second deformation elements, Fig. 4 an enlarged view of detail Z of Fig. 3 , with a separately shown second deformation element, Fig. 5 a second embodiment of the invention in perspective view, Fig. 6 a perspective sectional view according to the section line VI-VI in Fig. 5 , Fig. 7 a perspective sectional view according to the section line VII-VII in Fig. 5 Fig. 8 is an example for explanatory purposes in perspective view, and Fig. 9 is a perspective sectional view according to the section line IX-IX in Fig. 8 .

[0045] Fig. 1 explains the construction of an energy absorption device according to the prior art in comparison to an energy absorption device according to the invention.

[0046] A known bumper assembly for a motor vehicle, designated 102 in its entirety, comprises a bumper 104 (bumper crossmember) extending transversely along the motor vehicle, which is connected to the supporting structure of the motor vehicle via a left longitudinal member 106 and a right longitudinal member (not shown). The bumper 104 is provided with an energy absorption device formed by a first deformation element 108 arranged at the front of the bumper 104. A leading edge of a hood of the motor vehicle is designated 105. A radiator 107, among other components, is provided behind the bumper assembly 102, facing away from the direction of travel. The first deformation element 108 has a thickness D of, for example, 80 mm. The thickness D can be approximately constant in the transverse direction of the motor vehicle or vary in this direction.

[0047] The bumper assembly according to the invention, designated as a whole by 2, for a motor vehicle also includes a bumper 4 (bumper crossmember) extending in the transverse direction of the motor vehicle, which is connected to the supporting structure of the motor vehicle via a left and a right longitudinal member 6 (not shown). An energy absorption device with a first deformation element 8 is arranged at the front of the bumper 4. An outer and an inner second deformation element 10 are inserted into the first deformation element 8 on each side of the vehicle (only the right side is shown). A leading edge of the front hood of the motor vehicle is designated by 5. A radiator 7 is provided behind the bumper assembly 2, among other things.

[0048] The first deformation element 8 consists of a foam material, preferably a plastic material, for example EPP or PU, with a uniform density of approximately 30 g / l in the transverse, longitudinal, and vertical directions of the vehicle. The second deformation elements 10 also consist of a foam material, preferably a plastic material, for example EPP or PU. The density of the second deformation elements 10 is significantly higher than the density of the first deformation element 8 and is, for example, approximately 100 g / l.

[0049] Accordingly, the stiffness of the second deformation elements 10 is also significantly greater than the stiffness of the first deformation element 8. Therefore, the second deformation elements 10 are so-called "rigid foam parts".

[0050] The foam material of the first and / or second deformation element is, for example, a particle foam such as EPP. PUR foam is also a suitable option.

[0051] The first deformation element 8 has a thickness D of, for example, 80 mm in the sections where no second deformation element 10 is provided. In the areas with a second deformation element 10, the thickness D1 of the first deformation element 8 is, for example, 40 mm. The thickness D2 of the second deformation element 10 is, for example, 40 mm. "Thickness" here refers to the extent in the longitudinal direction of the vehicle.

[0052] The second deformation elements 10, for example, significantly reduce the penetration depth of the collision object in a standardized test procedure (e.g., a pendulum impact test) due to the local stiffening provided by the second deformation elements 10. This reduced penetration depth allows the leading edge 5 of the vehicle's hood to be pulled further forward than is possible in a vehicle designed according to the prior art.

[0053] In Fig. 2 A first deformation element 108 according to the prior art is shown, which is designed as a molded foam part. The outer contour of the first deformation element 108 is adapted to the inside of a bumper cover (not shown), so that the Fig. 2 The depicted "jagged" outer contour results. For example, the deformation element 108 has recesses 130 for PDC sensors and a recess 132 for a towing eye. The in Fig. 2 The non-visible rear side of the deformation element 108 is shaped according to the corresponding bumper 104 (not shown), in the sense of a large contact surface. Furthermore, a plurality of fixing arms 134 are visible, with which the first deformation element 108 can be positively engaged with the bumper 104.

[0054] Fig. 3 shows a first deformation element 8 according to the invention, which, with the exception of a right and a left recess 20 (in Fig. 4 (shown) identical to the first deformation element 108 according to Fig. 2 The recesses 20 serve, according to the invention, to receive a right and a left second deformation element 10. Furthermore, the first deformation element 8 has recesses 30 and 32 corresponding to the first deformation element 108, as well as fixing arms 34.

[0055] In Fig. 4 The key difference between the known deformation element 108 and the deformation element 8 according to the invention is shown enlarged. The second deformation element 10 is, for example, designed as a rigid foam body that can be clipped into the recess 20 of the first deformation element 8. The first deformation element 8 is, for example, designed as a molded foam part.

[0056] Fig. 5 Figure 1 shows a second embodiment of the invention. The deformation elements 8 and 10 of the embodiment according to Figure 1 are shown. Fig. 5 They are, for example, adapted to the design of a bumper cover for a specific equipment variant. Identical and functionally equivalent components are provided with the same reference numerals as in the first embodiment.

[0057] In contrast to the first embodiment, according to Fig. 5 The right and left second deformation elements 10 are geometrically different. Unlike the left second deformation element 10, the right second deformation element 10 has a recess 22 on its outer surface for a mounting bushing for a screw-in towing eye. Furthermore, a recess 24 for a cover for the opening for the towing eye is provided on the front of the right second deformation element 10.

[0058] The Fig. 6 und 7 The two deformation elements 10 are shown in enlarged sectional views. A channel 26 for receiving a fluid hose (not shown) for sensing an impact on the bumper 4 is shown on the rear side of the first deformation element 8.

[0059] The Fig. 8 und 9 Figure 1 shows an energy absorption device for explanatory purposes, comprising a first and a second deformation element 8 and 10, respectively. Both deformation elements 8 and 10 extend over a substantial portion of the width of a bumper (bumper crossmember), which is not shown. The first deformation element 8 is designed to rest fully against the bumper. It has recesses 40 into which fastening elements (e.g., mounting plugs) can be inserted for attachment to the bumper. A channel 26 for receiving a fluid hose 42 is provided on the rear side of the first deformation element 8, facing the bumper. The fluid hose 42 serves to detect an impact on the bumper.The adjacent channels 26a and 26b in the first deformation element 8 allow unimpeded deformation of the middle channel 26, so that the fluid hose 42 can deform optimally in the event of a pedestrian impact and thus sensing the impact in the best possible way.

[0060] The second deformation element 10 is strip-shaped and located in the lower region of the front face of the first deformation element 8, thus positioned in front of it. It is connected to the first deformation element 8, for example, by adhesive bonding. The second deformation element 10 projects beyond the first deformation element 8 at its lateral end sections. The height of the second deformation element 10 is approximately half that of the first deformation element 8. The second deformation element 10 is slightly thicker than the first deformation element 8. Recesses 44, 46, and 48 are provided on the front face and / or top surface of the second deformation element 10, for example, to accommodate a towing eye or to create space for PDC sensors.

[0061] The first deformation element 8 has a density of, for example, about 30 g / l, while the second deformation element 10 has a density of, for example, 130 g / l.

[0062] The presentation of Fig. 9 This is based on a CAD section view. For clarification, it should be noted that the two deformation elements 8 and 10 are of course made of solid materials.

[0063] The invention can be summarized as follows: An energy absorption device for a bumper 4 of a motor vehicle has a first deformation element 8 at the front of the bumper 4. The first deformation element 8 is a molded foam part extending over the width of the bumper 4 with a density of 20 to 50 g / l. At least one second deformation element 10 is inserted into the first deformation element 8, with a density at least 50 g / l higher than that of the first deformation element. Reference symbol list

[0064] 2 Bumper assembly 4 Bumper 5 Leading edge of the hood 6 Longitudinal member 7 Radiator 8 First deformation element 10 Second deformation element 20 Recess 22 Recess 24 Recess 26 Channel 26a Channel 26b Channel 30 Recess 32 Recess 34 Fixing arm 40 Recess 42 Pressure hose 44 Recess 46 Recess 48 Recess 102 Bumper assembly 104 Bumper 105 Leading edge of the hood 106 Longitudinal member 107 Radiator 108 First deformation element 130 Recess 132 Recess 134 Fixing arm D Thickness D1 Thickness D2 Thickness Z Detail

Claims

1. Energy absorption device for a bumper of a vehicle, comprising a first deformation element (8) extending substantially over the entire width of the bumper and at least two second deformation elements (10) which are arranged on the first deformation element (8), wherein the first and second deformation element (8, 10) consist of foam materials of different density, wherein the foam material of the first deformation element (8) has a density at least 50 g / l lower than the foam material of the second deformation element (10), wherein the density of the foam material of the first deformation element (8) is 20 to 50 g / l and the density of the foam material of the second deformation element (10) is 80 to 250 g / l, wherein the first deformation element (8) has in each case a recess (22) for receiving the second deformation element (10) and the second deformation element (10) is inserted into the first deformation element (8) and has a smaller extension in vehicle transverse direction, vehicle vertical direction and vehicle longitudinal direction compared to the first deformation element, wherein the second deformation element (10) is arranged on the front side or rear side of the first deformation element (8), and wherein the at least two second deformation elements (10) are arranged mirrorsymmetrically to a longitudinal center plane of the vehicle in the region of the extension of front longitudinal members of the vehicle.

2. Energy absorption device according to claim 1, wherein the foam material of the first deformation element (8) has a density at least 60 g / l lower than the foam material of the second deformation element (10).

3. Energy absorption device according to claim 1, wherein the foam material of the first deformation element (8) has a density at least 70 g / l lower than the foam material of the second deformation element (10).

4. Energy absorption device according to one of claims 1 to 3, wherein the density of the foam material of the second deformation element (10) is 90 to 250 g / l.

5. Energy absorption device according to one of claims 1 to 3, wherein the density of the foam material of the second deformation element (10) is 100 to 250 g / l.

6. Energy absorption device according to one of the preceding claims, wherein the second deformation element (10) is designed cuboid-like or pyramid-like.

7. Energy absorption device according to one of the preceding claims, wherein the second deformation element (10) is connected to the first deformation element (8) by form fit and / or adhesive bonding and / or by means of separate connecting elements.

8. Motor vehicle with an energy absorption device according to one of the aforementioned claims.

Images